Screen printing stencils can be produced by galvanoplastic means or by the formation of so-called photostencils. For this purpose, an already permeable surface array, e.g. a perforated foil or a screen fabric, for cylindrical stencils in form of a cylinder, is coated with a light-sensitive lacquer. After exposure to light of the pattern through a film superimposed over the light-sensitive lacquer layer and provided with the desired pattern, and subsequent development, one obtains a photostencil whose apertures are partly closed by the hardened light-sensitive lacquer, and are partly permeable to ink.
The production of such photostencils is very laborious. For each photostencil to be produced, a color separation pattern must be drawn, from which in the production of the film a line drawing must be prepared. Then the light-sensitive lacquer can be applied to the perforated foil. The coating of the foil must be done uniformly. After coating, the photo-sensitive lacquer is dried. In the meantime, after thoroughgoing inspection and retouching, the negative is converted in a contact frame to a halftone positive which has the same size as the photostencil to be produced.
The inspection and exact cutting of the combined film in an exact height of repeat and width of master is a very significant and labor intensive procedure incidental to the production of the film.
One then stretches the completed combined film over the photostencil blank, and carry out the exposure. The exposed stencil is then developed, and subsequently placed in a fusion chamber, whereby the light-sensitive lacquer hardens.
Subsequently, the stencil is again inspected and retouches. It can be seen that this procedure is very costly.